you need to wipe the drive or you need to add a drive or make a new partition. there is no downgrade, you can only install a lower OS on a clean drive.
May 08, 2010. Install Mac OS X 10.5 Leopard via USB on PowerPC Macs - Duration: 15:35. LOLZpersonok 177,106 views. Install leopard on powerbook g4 - Duration: 9:19. Johnmonk66 172,202 views. May 03, 2012. Jan 02, 2013. Confirmed: Mac OS X 10.5 Leopard will run on G4's Jun 12, 2007 - 16 Comments There has been some concern since the announcement that Leopard is a 64 bit operating system that those of us with 32 bit machines would be left in the dust with Tiger.
insert the DVD, reboot and hold down the C KEY select the DVD and install on the blank drive or partition. Obd auto doctor download.
This next part is not necessary, but I suggest If you only have the one boot drive reset the PRAM on your G4 only after the entire install process is complete
to reset PRAM see this link
repeat this 2/3 times
if you have more than one boot drive reset the PRAM, then hold down the OPTION KEY, select the drive/partition you want to boot from
Feb 12, 2018 10:04 AM
I have found that, by far, the easiest way to install Leopard on unsupported G4s is to spoof the clock speed in Open Firmware before installing. Spoofing will have Open Firmware tell OS X that your G4 is up-to-speed until you reboot. This will allow you to install without hacking an install disc or working in Target Disk Mode. You will still need to meet the 512 MB of RAM requirement, but I wouldn't suggest using less anyway.
Without further delay, here are some instructions I have passed on to a few friends already: Xbox 360 emulator mac.
Editor's note: Every Mac and Macintosh clone with PCI architecture supports Open Firmware, so this technique should work with any Mac that could possibly run Leopard. It completely eliminates the need to hack the installer on the Mac OS X 10.5 Leopard installer DVD. Be sure your firmware is up-to-date before attempting to install Leopard. (We have a field report indicating that this hack does not work with the 667 MHz and 800 MHz DVI G4 PowerBooks – on those models, you may need to reset min-cpu-frequency and max-cpu-frequency as well.)
Note that some third-party additions to the System can prevent Leopard from booting – Unsanity's Application Enhancer (APE) tops the list of add-ons – so you should make sure all of your software is up-to-date and may want to (or need to) disable System add-ons before installing Leopard. dk
To install Leopard on an 'unsupported' G4 clocked under 867 MHz:
1. Reboot your Mac and hold down the Cmd-Opt-O-F keys until you get a white screen with black text. This is the Open Firmware prompt.
2. Insert the Mac OS X Leopard Install DVD.
3. Type the following lines exactly as shown below into the Open Firmware prompt. Be mindful of capitalization, spaces, zeros, etc. If the command is properly typed and understood, Open Firmware will display 'ok' at the end of each line after you hit 'return'. What these lines do is set the CPU speed reported by Open Firmware to OS X as an 867 MHz G4 processor system. They then continue the boot from the DVD drive.
For single CPUs, use the following three lines:
For dual CPUs, use the following five lines:
4. Continue the install normally.
5. This CPU setting is only in effect until the Mac reboots. Once OS X Leopard is installed and your Mac has rebooted, the proper CPU speed should once again be displayed when you select About This Mac under the Apple menu.
This article was written by Dylan McDermond and first published on 2007.12.06. It was updated 2007.12.24.
UPDATE: The folks at iCode have taken the information from this article and used it to create LeopardAssist, a free program that automates this process and eliminates the need to fiddle with OpenFirware on your own.
Apple Powerbook G4 Laptop
Editor's note: Some readers have noted problems booting the Leopard install disc using the above commands. If so, substitute 'mac-boot' (without the quote marks) for the last line in the above Open Firmware commands. Also, if your Mac locks up hard during this process, resetting the PRAM (start your Mac and immediately hold down Cmd-Opt-P-R until your Mac restarts) should bring it back to life. dk
Further Reading
Powerbook G4 Laptop
- Using Open Firmware to Install Leopard below 867 MHz, The Mac Elite. Includes info on writing Open Firmware commands to a text file so you don't have to type them in.
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